In recent years, a thin plate for an electronic device, such as a semiconductor wafer, has been increased in size and decreased in thickness. For this reason, the thin plate is likely to be damaged. As a container for housing such thin plate to store and carry it, a multistage type housing cassette is described in Japanese Kokai 2004-273867. The multistage type housing cassette is a cassette capable of carrying an extremely thin wafer having a thickness of 20 to 100 μm without chipping of an outer circumferential surface of the wafer and also without erroneous suction of it on a pad. This housing cassette has a plurality of housing racks arranged at equal intervals and stacked in a multistage form through a support.
However, such a multistage type housing cassette only supports a circumferential edge of the extremely thin wafer from its bottom side, but is not provided with means for securely constraining the extremely thin wafer. For this reason, if the multistage type housing cassette is tilted, the wafer may be easily displaced and damaged, so that it is necessary to carry the cassette carefully. Also, the cassette is not configured to seal its interior to isolate the wafer from the external environment. For this reason, the cassette can neither seal the wafer to isolate it from the external environment, nor securely support it.
For these reasons, the present inventor has proposed a thin plate container capable of isolating thin plates, such as semiconductor wafers, from an external environment and securely supporting and carrying it. An example of the thin plate container is illustrated in FIG. 8. As illustrated in the drawings, a thin plate container 1 mainly consists of a plurality of loading trays 2. The loading trays 2 are configured to be mutually removable, and the thin plate container includes the plurality of loading trays 2, on which the thin plates are loaded, coupled with each other to form a stack.
The thin plate container 1 described as above does not have any particular problem if it is used in a factory or the like; however, if it is carried, it has problems with sealing and shock resistance.
The thin plate container 1 includes the plurality of loading trays 2 coupled with each other to form a stack, so that if it receives a shock, each of the loading trays 2 may be slightly displaced, or the seal between the respective loading trays 2 may be reduced.